Solid state power controllers (SSPCs) are often used in power distribution systems to protect electrical systems from overload conditions. SSPCs often employ I2t over-current protection. I2t protection allows over-currents for a short amount of time based upon a threshold power flow. These over-currents may be, for example, 800% to 1000% of the steady-state current. Because of this, the SSPCs are required to have a high accuracy current sensor with a wide measuring range. For example, if a steady-state current is 200 amps, the current sensor must be able to accurately sense up to 2000 amps.
In the past, resistive shunts and Hall effect sensors have been used for current sensing in SSPCs. Resistive shunts, however, have power losses that can be quite high when required to support large over-currents. Hall effect sensors are non-contact sensors that sense current based upon a magnetic field created by current flowing in a conductor. These sensors include a core that is implemented around the conductor in which most of the magnetic field generated by the current is concentrated. The core includes an air gap, with a Hall effect device mounted in the air gap of the core at a right angle to the concentrated magnetic field. The Hall effect device produces a voltage that is proportional to the current in the conductor. The larger the current in the conductor, the larger the size of the Hall effect sensor that is required in order to provide accurate measurements. It is desirable to limit the size of these current sensors in order to reduce the size and weight of the SSPC.